I lost a dog many years ago to a collar accident. We switched to Chinook Break-away collars, and don't leave anything else on the dogs. They are much safer, you can put tags on them, and you can grab both rings quickly to keep an exuberant dog from bolting, if needed. (The company has GREAT customer service -- when mine were young, they figured out how to get the collars off and use them as tug-of-war toys, and Chinook sold me replacements at a deep discount, even though it was no fault of theirs, as I had to replace them several times until the dogs tired of that game.)